Plasma processing apparatus

Abstract

Detection accuracy of a power of a progressive wave and detection accuracy of a power of a reflection wave can be improved. In a plasma processing apparatus, a first directional coupler is provided in a first waveguide which is configured to connect a microwave generating unit and a first port of a circulator. A first detector is connected to the first directional coupler. A second port of the circulator is connected to a plasma generating unit via a second waveguide. Further, a second directional coupler is provided in a third waveguide which is configured to connect a third port of the circulator and a dummy load. A second detector is connected to the second directional coupler.

We claim: 
     
       1. A plasma processing apparatus, comprising:
 a processing vessel; 
 a microwave generating unit configured to generate a microwave; 
 a plasma generating unit configured to generate plasma within the processing vessel with the microwave; 
 a circulator, having a first port, a second port and a third port, configured to output the microwave received through the first port to the second port and output the microwave received through the second port to the third port; 
 a first waveguide configured to connect the microwave generating unit and the first port; 
 a second waveguide configured to connect the second port and the plasma generating unit; 
 a tuner provided in the second waveguide, equipped with a first movable plate and a second movable plate, and configured to adjust a protruding amount of each of the first and second movable plates toward an internal space of the second waveguide; 
 a third waveguide provided between the third port and a dummy load; 
 a first directional coupler, connected to an internal space of the first waveguide through a pair of holes, configured to output a part of the microwave which is propagated from the microwave generating unit to the first port; 
 a first detector, connected to the first directional coupler, configured to detect a power of a progressive wave which is the part of the microwave output from the first directional coupler; 
 a second directional coupler, provided in the third waveguide, configured to output a part of the microwave which is propagated from the third port to the dummy load; 
 a second detector, connected to the second directional coupler, configured to detect a power of a reflection wave which is the part of the microwave output from the second directional coupler; and 
 a controller including a processor connected to the first detector, the second detector, the microwave generating unit and the tuner, 
 wherein the controller is configured to generate by using an IQ digital converter, the microwave including multiple frequency components having different frequencies belonging to a preset frequency band, and configured to set phases of adjacent frequency components to be orthogonal to each other, and 
 wherein the controller is configured to control a power of the microwave generated by the microwave generating unit such that a power supplied to the plasma generating unit is maintained constant according to a sum of the power of the progressive wave detected by the first detector and the power of the reflection wave detected by the second detector, and control the tuner to adjust the protruding amount of each of the first and second movable plates according to the power of the reflection wave detected by the second detector.